A high-precision sapphire valve seat ball groove grinding method and grinding device

Abstract

The present application relates to gem valve seat processing technical field, especially a kind of high-precision sapphire valve seat ball groove grinding method, first, the sapphire blank is finished sapphire valve seat's spherical groove;In new grinding device, sapphire valve seat precision forming blank is placed in center positioning hole, add fine grinding paste to start grinding device and grind fine sapphire valve seat after grinding, sapphire valve seat is placed in center positioning hole, after sapphire ball is bonded in the lower end of swing lever, it is placed in the spherical groove of sapphire valve seat, add fine grinding paste and grind;Matched sapphire ball is placed in the spherical groove of sapphire valve seat after fine grinding, after adding grinding liquid, grinding damper pad and sapphire ball are contacted to start grinding;The present application realizes the automation of high-precision gem valve seat and batch production, so that valve seat surface finish effect and quality are more stable, the efficiency of valve seat is improved, the pass rate of product is greatly improved, and production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of sapphire valve seat grinding technology, and in particular to a grinding method and grinding apparatus for high-precision sapphire valve seat ball grooves. Background Technology

[0002] Due to their excellent physicochemical properties, sapphire and ruby ​​are commonly used in valve seat assemblies. Sapphire is typically used for the valve base, and ruby ​​for the sealing sphere. This is due to the high hardness (Mohs 9), high compressive strength, and excellent resistance to high temperatures and acid / alkali corrosion of these gemstone materials. Gemstone valve seats are widely used in civilian medical applications, high-precision measuring instruments, aerospace, and other fields. They are also frequently used in flow control valves or check valves, such as check valves for liquid chromatographs, check valves for constant flow pumps, flow meter ball valves, four-way directional flow valves, and ventilator flow control valves. The sealing pressure requirement for sapphire valve seats with sapphire for the valve base and ruby ​​for the sealing sphere is typically 20–30 MPa or less. For flow valves, the sealing requirements of the mating surfaces of the sapphire valve seat and the ruby ​​ball are not very high. However, for check valves, the sealing requirements of the mating surfaces are very high, and the sealing pressure value of the mating surfaces is often required to be above 30MPa, or even 50MPa. Therefore, the requirements for the precision of the ruby ​​ball and the fit of the sapphire valve seat are high.

[0003] The existing manufacturing process for jewel valve seats is as follows:

[0004] After the initial shaping of the sapphire base groove, the sapphire valve seat groove is then precision shaped. The third step is to manually fit the sapphire valve seat and the ruby ​​sphere. Finally, the finished product is inspected and packaged for shipment.

[0005] The shortcomings of existing methods are:

[0006] 1) Sapphire valve seats are mainly assembled manually, resulting in extremely poor interchangeability of parts;

[0007] 2) The sapphire valve seat is lapped manually on a machine tool. Since only the valve seat rotates, the lapped ball is manually swung and does not rotate. The efficiency of manual lapping is very low. Furthermore, the quality of the sapphire valve seat is affected by various factors such as equipment precision, motion mode and worker operating skills, resulting in extremely unstable surface finish and quality. The product qualification rate is low and the production cost is extremely high.

[0008] 3) It requires high precision from the molding equipment and high operational skills from the operators;

[0009] 4) To reduce and minimize the factors that cause chipping and other machining defects during the sapphire valve seat preparation process, a significant investment of manpower, resources, and raw materials is necessary. Existing processing techniques simply cannot achieve the desired results. Furthermore, this significantly increases the difficulty of machining the product's groove shape, leading to low work efficiency and high production costs.

[0010] 5) Currently, high-precision sapphire valve seat products can only be produced in sample form and cannot be supplied in large quantities. Summary of the Invention

[0011] To address the shortcomings of the existing technologies, this invention provides a grinding method and apparatus for high-precision sapphire valve seat ball grooves. The aim is to solve the technical problems of existing high-precision sapphire valve seat ball grooves, which can only be manually fitted, have extremely poor interchangeability of parts, highly unstable surface finish and quality, low product qualification rate, high production costs, high requirements for equipment precision and operator skills, complex processing procedures and difficulties in sapphire valve seat production, and the inability to mass-produce them.

[0012] The technical solution adopted by this invention to solve its technical problem is:

[0013] A method for grinding high-precision sapphire valve seat ball grooves includes the following steps:

[0014] S1. Precision forming: The qualified sapphire blank is directly precision machined into a spherical groove for the sapphire valve seat using the generating method on a groove machining equipment; the radius of curvature SR of the machined spherical groove is 0.025~0.02mm larger than the size of the ground sphere.

[0015] S2. Fine Grinding: Using a new type of grinding device, place the sapphire valve seat preform into the center positioning hole of the grinding sand seat connected to the main shaft of the grinding device, then add fine grinding paste, and place the swing arm with the grinding ball fixed in it into the spherical groove of the sapphire valve seat; adjust the speed of the main shaft of the grinding device to 300-1200 rpm; the length of the swing arm to 15-50 mm, the cone angle of the swing arm to 30-90°, and the swing angle of the swing arm to 3-45°; the diameter of the grinding ball is 0.001-0.005 mm larger than the ruby ​​ball, and the fine grinding time is 1-6 minutes. Finally, start the swing arm of the grinding device to perform a circular motion to grind the spherical groove and then stop.

[0016] S3. Fine grinding: Place the finely ground sapphire valve seat into the center positioning hole, attach the ground ruby ​​ball to the lower end of the rocker arm and place it in the spherical groove of the sapphire valve seat, add fine grinding paste; adjust the spindle speed to 200-600 rpm, the fine grinding time to 6-12 minutes, and finally start the grinding device to grind, and stop after grinding is completed.

[0017] S4. Ultra-precision grinding: Place the matching ruby ​​ball into the spherical groove of the precision-ground sapphire valve seat, add grinding fluid, and make contact with the grinding damping pad fixed on the lower end of the upper pressure rod; adjust the spindle speed to 5-200 rpm, and stop grinding when the surface roughness of the spherical groove reaches Ra0.008-Ra0.012; finally, clean the sapphire valve seat and ruby ​​ball, and package them together for shipment.

[0018] Preferably, the fine polishing paste in step S2 is a mixture of synthetic diamond micron powder with a particle size of JRW3.5 or less and organic matter; the concentration of the fine polishing paste is 1 / 3 to 1 / 2 of the concentration of the fine polishing paste.

[0019] Preferably, the grinding balls in step S2 are grade 5 to 10 grinding steel balls; the grinding steel balls are used 3 to 12 times.

[0020] Preferably, the fine polishing paste in step S3 is a mixture of synthetic diamond micron powder with a particle size of JRW1.5 or less and organic matter, and the concentration of the fine polishing paste is 1 / 3 to 1 / 2 of the concentration of the fine polishing paste.

[0021] Preferably, in step S3, the ruby ​​sphere is replaced 1 to 2 times during grinding, and the surface roughness of the sapphire valve seat spherical groove after fine grinding is Ra0.025 to Ra0.012.

[0022] Preferably, the polishing fluid in step S4 is a chemical polishing fluid.

[0023] A high-precision sapphire valve seat ball groove grinding device includes a machine tool connecting seat, a spindle is disposed inside the machine tool connecting seat, a grinding seat is fixedly disposed on the top of the spindle, and a center positioning hole for mounting the sapphire valve seat is provided on the top of the grinding seat; it also includes a bracket, a fixed pressure rod is vertically disposed on the bracket, and a first grinding mechanism for fine grinding and precision grinding or a second grinding mechanism for ultra-precision grinding is disposed at the lower end of the fixed pressure rod. A grinding ball or a grinding ruby ​​ball is bonded to the lower end of the first grinding mechanism; a grinding damping pad is bonded to the lower end of the second grinding mechanism; the grinding ball or the grinding ruby ​​ball mates with the sapphire valve seat ball groove.

[0024] Preferably, the first grinding mechanism includes a buffer rod and a swing rod. The bottom of the fixed pressure rod is provided with a mounting hole, the top of the buffer rod is fixed in the mounting hole, the bottom surface of the buffer rod is provided with a swing hole in a conical structure, the top of the swing rod is provided with a mating part in a conical structure, and the swing hole of the mating part of the swing rod abuts against the mating part; the bottom of the swing rod is bonded with a grinding ball or a grinding ruby ​​ball that mates with the spherical groove of the sapphire valve seat.

[0025] Preferably, the second grinding mechanism includes an upper pressure rod, the bottom of which is provided with a mounting hole, the upper end of which is fixed in the mounting hole, and the lower end of which is fixed with a grinding damping pad, which cooperates with a grinding ruby ​​ball placed in the spherical groove of the sapphire valve seat.

[0026] Preferably, a buffer spring is provided on the outer side wall of the top of the buffer rod or the upper pressure rod, and the buffer spring is located in the mounting hole.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1) This invention, through ingenious improvements to some structures of existing grinding machines and adjustments to the process parameters of the grinding device, fully realizes the automated grinding and fitting of sapphire valve seat spherical grooves. It transforms the original manual single-piece processing and fitting into automated multi-piece processing and fitting, enabling not only mass production of high-precision sapphire valve seats but also significantly improving the grinding and fitting efficiency of high-precision sapphire valve seats, shortening the production cycle, and noticeably reducing production costs. Furthermore, it significantly enhances the interchangeability of sapphire valve seat components, making high-precision sapphire valve seats more adaptable.

[0029] 2) This invention realizes the automated grinding and fitting of high-precision sapphire valve seats. As long as the operating parameters of the grinding device are set consistently, the grinding times of the grinding balls and the grinding ruby ​​balls are ensured, so that the quality of the final high-precision sapphire valve seat can be effectively guaranteed. This avoids the impact of various uncertain factors on the grinding and fitting quality of the sapphire valve seat, resulting in a high pass rate of automated grinding and fitting of sapphire valve seat products and a significant reduction in production costs.

[0030] 3) The high-precision sapphire valve seat grinding method and grinding device provided by the present invention allow workers to simply install and place the equipment, sapphire valve seat and grinding balls, and replace the grinding balls periodically. This reduces the skill requirements for processing equipment and workers, simplifies the processing technology and increases the grinding speed.

[0031] 4) For products with low sealing requirements, only a fine grinding process is needed to meet the requirements in this invention. Furthermore, the grinding process will not cause the sapphire valve seat to develop chips or other processing defects, thus significantly improving the product qualification rate.

[0032] 5) This invention does not require modifications to existing grinding equipment; simply adding grinding and fitting components as needed achieves normal valve seat groove grinding and fitting. This grinding equipment has a simple structure and is easy to operate. Fine grinding, precision grinding, and ultra-precision grinding can be achieved on the same equipment; it reduces the labor intensity of operators, improves grinding and fitting efficiency, and has extremely low processing equipment costs. Furthermore, this invention allows for the replacement of corresponding grinding and fitting components according to different product specifications, enabling the grinding and fitting of various specifications of jewel valve seats. The tooling can be easily replaced when worn, resulting in good equipment adaptability and a long service life. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort:

[0034] Figure 1 This is a schematic diagram of the structure of an embodiment of a high-precision sapphire valve seat ball groove grinding method and grinding device according to the present invention.

[0035] Figure 2 This is another structural schematic diagram of an embodiment of a high-precision sapphire valve seat ball groove grinding method and grinding device in this invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, a clear and complete description will be provided below in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] The terms “first,” “second,” “third,” etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0039] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] A preferred embodiment of the present invention provides a method for grinding the ball groove of a high-precision sapphire valve seat 5, comprising:

[0041] S1. Precision forming: The qualified sapphire blank is directly precision machined into a spherical groove for the sapphire valve seat 5 using the generating method on a groove machining equipment; the radius of curvature SR of the machined spherical groove is 0.025~0.02mm larger than the size of the ground sphere 8.

[0042] S2. Fine Grinding: Using a new type of grinding device, place the sapphire valve seat 5 precision-formed blank into the center positioning hole 4 of the grinding sand seat connected to the main shaft 2 of the grinding device, then add fine grinding paste, and place the swing rod 11 with the grinding ball 8 fixed in it into the spherical groove of the sapphire valve seat 5; adjust the speed of the main shaft 2 of the grinding device to 300-1200 rpm; the length of the swing rod 11 to 15-50 mm, the cone angle of the swing rod 11 to 30-90°, and the swing angle of the swing rod 11 to 3-45°; the diameter of the grinding ball 8 is 0.001-0.005 mm larger than the ruby ​​ball; the fine grinding time is 1-6 minutes; finally, start the grinding device to start the swing rod 11 to perform circular motion to grind the spherical groove and then stop.

[0043] S3. Fine grinding: Place the finely ground sapphire valve seat 5 into the center positioning hole 4, attach the grinding ruby ​​ball to the lower end of the rocker arm 11 and place it in the spherical groove of the sapphire valve seat 5, add fine grinding paste; adjust the speed of the spindle 2 to 200-600 rpm, the fine grinding time to 6-12 minutes, and finally start the grinding device to grind, and stop after grinding is completed.

[0044] S4. Ultra-precision grinding: Place the matching ruby ​​ball into the spherical groove of the precision-ground sapphire valve seat 5, add grinding fluid, and make contact with the grinding damping pad 9 fixed on the lower end of the upper pressure rod 16; adjust the speed of the spindle 2 to 5-200 rpm, and stop grinding when the surface roughness of the spherical groove reaches Ra0.008-Ra0.012; finally, clean the sapphire valve seat 5 and the ruby ​​ball, and package them together for shipment.

[0045] In specific implementation, the fine grinding paste in step S2 is a mixture of synthetic diamond micro powder with a particle size of less than JRW3.5 and organic matter, and the mixing ratio of diamond micro powder to organic matter is 1:25 to 1:100; the organic matter is a mixture of oleic acid, petrolatum and fat.

[0046] In specific implementation, the grinding ball 8 in step S2 is a grade 5 to 10 grinding steel ball; the grinding steel ball is used 3 to 12 times.

[0047] In specific implementation, the fine polishing paste in step S3 is a mixture of synthetic diamond micron powder particles with a particle size of JRW1.5 and below and organic matter, and the concentration of the fine polishing paste is 1 / 3 to 1 / 2 of the concentration of the fine polishing paste.

[0048] In specific implementation, the ruby ​​spheres used in step S3 are replaced 1 to 2 times, and the surface roughness of the sapphire valve seat 5 spherical groove after fine grinding is Ra0.012 to Ra0.025.

[0049] In specific implementation, the polishing fluid in step S4 is a chemical polishing fluid. This shortens the ultra-precision polishing time and ensures that the surface roughness of the spherical groove reaches Ra0.008~Ra0.012, meeting the requirements of high-precision sapphire valve seats.

[0050] A high-precision grinding device for the spherical groove of a sapphire valve seat 5 includes a machine tool connecting seat 1, in which a spindle 2 is disposed and connected to a power mechanism; a grinding seat 3 is fixedly disposed on the top of the spindle 2, and a center positioning hole 4 for mounting the sapphire valve seat 5 is disposed on the top of the grinding seat 3; it also includes a bracket 6, on which a fixed pressure rod 7 is vertically disposed; the lower end of the fixed pressure rod 7 is provided with a first grinding mechanism for fine grinding and precision grinding or a second grinding mechanism for ultra-precision grinding; a grinding ball 8 or a grinding ruby ​​ball is bonded to the lower end of the first grinding mechanism; a grinding damping pad 9 is bonded to the lower end of the second grinding mechanism; the grinding ball 8 or the grinding ruby ​​ball mates with the spherical groove of the sapphire valve seat 5.

[0051] For specific implementation, please refer to the appendix. Figure 1The first grinding mechanism includes a buffer rod 10 and a swing rod 11. The bottom of the fixed pressure rod 7 has a mounting hole 12. The top of the buffer rod 10 is fixed in the mounting hole 12 by a locking bolt 14. A conical swing hole 13 is provided on the bottom surface of the buffer rod 10. The top of the swing rod 11 has a conical mating part 15, and the swing hole 13 of the mating part 15 of the swing rod 11 abuts against the mating part. A grinding ball 8 or a grinding ruby ​​ball that mates with the spherical groove of the sapphire valve seat 5 is bonded to the bottom of the swing rod 11. This configuration allows the swing rod 11 to perform fine and precise grinding of the sapphire valve seat during circular motion. The structure is simple, replacement is quick, and the ground sapphire valve seat meets the requirements for low-precision sapphire valve seats. Therefore, the sapphire valve seat after fine and precise grinding can be directly used in equipment with lower precision.

[0052] For specific implementation, please refer to the appendix. Figure 2 The second grinding mechanism includes an upper pressure rod 16. A mounting hole 12 is provided at the bottom of the fixed pressure rod 7. The upper end of the upper pressure rod 16 is fixed in the mounting hole 12 by a locking bolt 14. A grinding damping pad 9 is fixed to the lower end of the upper pressure rod 16. The grinding damping pad 9 mates with a grinding ruby ​​ball placed in the spherical groove of the sapphire valve seat 5. This simple structure allows for ultra-fine grinding of the sapphire valve seat by simply changing parts within the same device. This results in higher precision in the fit between the sapphire valve seat 5 and the ruby ​​ball, fully meeting the requirement of a pressure of 30-50 MPa for the sapphire valve seat, enabling its use in high-precision devices.

[0053] In specific implementation, a buffer spring 17 is provided on the outer wall of the top of the buffer rod 10 or the upper pressure rod 16, and the buffer spring 17 is located in the mounting hole 12. This makes the movement of the swing rod 11 and the upper pressure rod 16 smoother, and also enables the grinding device to achieve flexible compensation during the movement, reducing the possibility of breakage of the workpiece being ground. In addition, it also makes the grinding quality of the spherical groove surface of the sapphire valve seat 5 better, and makes the fit accuracy of the sapphire valve seat 5 and the ruby ​​sphere higher after grinding.

[0054] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for grinding high-precision sapphire valve seat ball grooves, characterized in that, The grinding device includes a machine tool mounting base, within which a spindle is housed. A grinding seat is fixedly mounted on the top of the spindle, and the top of the grinding seat has a central positioning hole for mounting a sapphire valve seat. It also includes a support frame, on which a fixed pressure rod is vertically mounted. The lower end of the fixed pressure rod is equipped with a first grinding mechanism for fine and high-precision grinding, or a second grinding mechanism for ultra-fine grinding. A grinding ball or a grinding ruby ​​ball is bonded to the lower end of the first grinding mechanism; a grinding damping pad is bonded to the lower end of the second grinding mechanism. The grinding ball or grinding ruby ​​ball mates with the spherical groove of the sapphire valve seat. The mechanism includes a buffer rod and a swing rod. The bottom of the fixed pressure rod has a mounting hole, and the top of the buffer rod is fixed within the mounting hole. The bottom surface of the buffer rod has a conical swing hole, and the top of the swing rod has a conical mating part. The swing hole of the mating part of the swing rod abuts against the mating part. A grinding ball or a grinding ruby ​​ball that mates with the spherical groove of a sapphire valve seat is adhered to the bottom of the swing rod. The second grinding mechanism includes an upper pressure rod, the upper end of which is fixed within the mounting hole. The lower end of the upper pressure rod is fixed with a grinding damping pad, which mates with the grinding ruby ​​ball placed within the spherical groove of the sapphire valve seat. Includes the following steps, S1. Precision forming: The qualified sapphire blank is directly precision machined into a spherical groove for the sapphire valve seat using the generating method on a groove machining equipment; the radius of curvature SR of the machined spherical groove is 0.025~0.02mm larger than the size of the ground sphere; S2. Fine Grinding: Place the sapphire valve seat preform into the center positioning hole of the grinding sand seat connected to the spindle of the grinding device, then add fine grinding paste. Place the swing arm with the grinding ball fixed in place in the spherical groove of the sapphire valve seat. Adjust the spindle speed of the grinding device to 300-1200 rpm; the length of the swing arm to 15-50 mm, the cone angle of the swing arm to 30-90°, and the swing angle of the swing arm to 3-45°; the diameter of the grinding ball is 0.001-0.005 mm larger than the ruby ​​ball; the fine grinding time is 1-6 minutes; finally, start the swing arm of the grinding device to perform circular motion to grind the spherical groove and then stop. S3. Fine grinding: Place the finely ground sapphire valve seat into the center positioning hole, attach the ground ruby ​​ball to the lower end of the rocker arm and place it in the spherical groove of the sapphire valve seat, add fine grinding paste; adjust the spindle speed to 200-600 rpm, the fine grinding time to 6-12 minutes, and finally start the grinding device to grind, and stop after grinding is completed. S4. Ultra-precision grinding: Place the matching ruby ​​ball into the spherical groove of the precision-ground sapphire valve seat, add grinding fluid, and make contact with the grinding damping pad fixed on the lower end of the upper pressure rod; adjust the spindle speed to 5-200 rpm, and stop grinding when the surface roughness of the spherical groove reaches Ra0.008-Ra0.012; finally, clean the sapphire valve seat and ruby ​​ball, and package them together for shipment.

2. The grinding method for the high-precision sapphire valve seat ball groove as described in claim 1, characterized in that, The fine grinding paste in step S2 is a mixture of synthetic diamond micro powder with a particle size of less than JRW3.5 and organic matter, with a mixing ratio of diamond micro powder to organic matter of 1:25 to 1:

100.

3. The grinding method for the high-precision sapphire valve seat ball groove as described in claim 1, characterized in that, The grinding balls in step S2 are grade 5 to 10 grinding steel balls; the grinding steel balls are used 3 to 12 times.

4. The grinding method for the high-precision sapphire valve seat ball groove as described in claim 1, characterized in that, The fine polishing paste in step S3 is a mixture of synthetic diamond micro powder with a particle size of JRW1.5 and below and organic matter, and the concentration of the fine polishing paste is 1 / 3 to 1 / 2 of the concentration of the fine polishing paste.

5. The grinding method for the high-precision sapphire valve seat ball groove as described in claim 1, characterized in that, In step S3, the ruby ​​spheres are replaced 1 to 2 times during grinding, and the surface roughness of the sapphire valve seat spherical groove after fine grinding is Ra0.025 to Ra0.

012.

6. The grinding method for the high-precision sapphire valve seat ball groove as described in claim 1, characterized in that, The polishing fluid in step S4 is a chemical polishing fluid.

7. The grinding method for the high-precision sapphire valve seat ball groove as described in claim 1, characterized in that, A buffer spring is provided on the outer side wall of the top of the buffer rod or the upper pressure rod, and the buffer spring is located in the mounting hole.

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